Fuel pump drive



7 Oct. 8, 1963 Y A. E. KOLBE 3,106,168

FUEL PUMP DRIVE Filed Sept. 17, 1959 IN VEN TOR.

A 7" TORNE Y United States Patent 6 {gamed 0... 8, 1963 3,106,168 FUEL PUMP DRIVE Adelbert E. Kolbe, Berkley, MiclL, assignor to General Motors Corporation, Detroit, Miclr, a corporation of Delaware Filed Sept. 17, 1959, Ser. No. 840,677 1 Claim. (Cl. 103205) This invention relates to fuel drive means for internal combustion engines and is especially applicable for driving a fuel pump from a crankshaft of an internal combustion engine to be used for automotive and other purposes.

It is proposed to drive a fuel pump from the crankshaft of a four stroke cycle internal combustion engine, which runs at twice the speed of the camshaft. To do this it is proposed to provide a short stroke fuel pump to proporitonally reduce the stroke of the drive for the fuel pump. The drive is directly aligned with the reciprocating shaft of the fuel pump and may be positioned in oblique relation to the axis of the crankshaft of the engine. The fuel pump also may be removed from the engine with or without removing the drive.

In the drawing:

The single FIGURE of the drawing is a fragmentary view of one end of an internal combustion engine with a fuel pump drive embodying the invention mounted in oblique relation to the axis of the crankshaft of the engine.

The engine 10 has a frame 11 in which bearings 12 are provided for supported the journals 13 of the crankshaft 14 of the engine 10. The crankshaft 14 has an end 16 that projects into a cavity 17 in a housing 18 that forms a part of the frame 11 and is removably secured to a front end wall 19 by bolts or other suitable means, not shown. The cavity 17 has an inlet 21 in which a filler tube 22 may be secured for filling with oil the crankcase of the engine communicating with the cavity 17. The end 16 supports a cam 23, which may if desired be of conical formation and supports a gear 24 which may be employed in operating a distributor and lubricating oil pump, also not shown. Beyond the gear 24 is an oil slinger 26 and a hub 27 employed in driving a pulley 28 for driving the engine fan and other accessory apparatus, not shown. The hub 27, the slinger 26, the gear 24 and the cam 23 all may be secured against a shoulder 29 formed on the shaft end 16 by employing a collar 31 secured in the hub 27 by a bolt 32 which is threaded into an opening in the end of the shaft end 16. A seal 33 is employed adjacent the outer edge of the slinger 26 and is press fitted into an opening 34 formed in the housing 18 around the hub 27. The cam 23, the gear 24 and the hub 27 may be keyed to the shaft end 16 as is indicated at 36 and 37.

The housing 18 may be formed to provide a push rod guide 38 which may have an insertable guide sleeve indicated at 39. The guide 38 is adapted to receive a reciprocating push rod 40, the inner end of which is normally disposed on the surface of the cam 23. The push rod 40 is disposed in the plane of the axis of rotation of the crankshaft 14 and in alignment with a socket or cavity 41 formed in the exterior surface of the housing 18. Secured in the outer end of the cavity 41 is the cylindrical shank 42 of the casing 43 of a fuel pump 44 for the engine 10. The fuel pump casing 43 may be removably secured in the cavity 41 by operation of a set screw 46. The fuel pump 44 has the usual pressure equalizing chamber 47 separated by diaphragm 48 from the inlet and exhaust chambers of the pump 49 and 51 respectively. The pump has inlet and exhaust valves 52 and 53 respectively that control the flow of fuel in the pumping chamber 54 that is formed by the diaphragms 56 and 57. The diaphragms 56 and 57 are secured between the separable sections of the pump casing 43 by operation of the screws 58. The middle of the diaphragm 57 is secured by plates 59 and a bolt 61 to the enlarged end 62 of a reciprocating drive shaft 63. The drive shaft 63 is mounted in the casing 43 on a shaft guide indicated at 64. The inner end of the shaft 63 projects through a cavity 65 in the shank 42 and into a part of the cavity 41 that extends beyond the shank 42. The inner end of the shaft 63 is adapted to be seated in a recess 66 that is formed in the end of a coupling 67 that is press fitted on the outer end of the push rod 46. The recess 66 is aligned with the shafts 63 and 40. The coupling 67 has a flange 68 adapted to engage the end of a spring 69 which is normally compressed against the inner end of the cavity 41 by the operation of the main actuating spring 71 of the pump 44. The spring 71 tends to compress the plates 59 carrying the diaphragm 57 for displacing fuel from the pump chamber 54 and through the exhaust valve 53. The spring 69 and the cam 23 tend to move the shafts 46 and 63 against the spring 71 for drawing fuel through the inlet valve 52 and into the pumping chamber 54. When the engine is running there is sometimes a demand for less fuel than the full capacity of the pump, for example, during engine idle. This reduced demand causes a temporary and partial hydraulic lock between the inlet valve 52 and the carburetor. When this occurs, chamber 54 tends to fill with fuel and diaphragms 56 and 57 are urged toward their intake or maximum stroke position thus tending to compress the spring 71 to hold the shaft 63 outwardly of the recess 66 in the socket 67. However, the spring 69 will tend to cause the socket 67 to follow the end of the shaft 63 and to move the shaft 40 away from the cam 23. This will cause the pump to operate at the stroke which is less than the lift of the cam 23 to deliver a reduced quantity of fuel when there is a reduced demand for fuel. This may occur for example when the motor vehicle with which the engine 10 may be employed is running down hill and driving the engine at no load.

What is claimed is:

A pump and pump drive unit comprising a housing having a pump pressure chamber formed therein, a reciprocable diaphragm defining one wall of said chamber, a first spring acting on said diaphragm to decrease the volume of said chamebr, a reciprocable diaphragm drive shaft secured to said diaphragm and urged by said first spring in the chamber decreasing volume direction, a push rod reciprocably received in said housing and engaging said drive shaft, a second spring having less spring force than said first spring and acting on said push rod to maintain said push rod in engaging relation with said said drive shaft and forcibly opposing said first spring, and a lift cam separably engageable with said push rod for reciprocating said push rod, said first spring being variably opposed by pump output pressure in said chamber in accordance with pump output demand to vary the diaphragm stroke, said second spring force lifting said push rod from said cam when said pump output pressure decreases the pump diaphragm stroke in accordance With the decrease of the pump diaphragm stroke.

References Cited in the file of this patent UNITED STATES PATENTS 5 798,083 Swenson Aug. 29, 1905 1,639,623 White Aug. 16, 1927 4 Hurst Dec. 15, 1936 Hoffer Sept. 28, 1937 Lowther Dec. 15, 1942 Lasley Mar. 31, 1953 Smith Jan. 31, 1961 FOREIGN PATENTS 

